The use of copper compounds in the halogenation of aliphatic and aromatic hydrocarbons by oxyhydrohalogenation is of course well known in the art. In general, these compounds have been impregnated on a substantially inert support such as silica or alumina or the like. In the patent literature alone, there are literally hundreds of prior art publications discussing the use of cupric chloride per se, catalysts comprising an alumina or silica support impregnated with cupric chloride, and catalyst compositions involving combinations of cupric chloride and other metal chlorides, including potassium and other alkali metal chlorides.
As one example, mention might be made of U.S. Pat. No. 3,148,222 issued Sept. 8, 1964, which discloses and claims a process for chlorinating benzene and other aromatic hydrocarbons using a copper chloride-lithium chloride catalyst of an inorganic catalyst support, the preferred support being activated F-1 alumina which contains about 0.8% sodium oxide.
There are many major process variables which will affect the type and specific properties of the catalyst employed, including such things as the type of reactor (fixed or fluid bed, etc.) the nature of the hydrocarbon feed stock (saturated or unsaturated, aromatic or aliphatic), the source of chlorine or other halogen to be employed (chlorine gas in oxychlorination, hydrochloric acid in oxyhydrochlorination), to mention a few.
In all cases, there are however a number of specific desired chemical, physical or process characteristics which are common to all of the situations. These include in every case, the ability of the catalyst to provide efficient conversion of hydrocarbon feed stock to chlorinated hydrocarbon end products.
In the past, those skilled in the art have sought a socalled "selective catalyst," that is to say a catalyst which would provide selective chlorination of the hydrocarbon feed stock to a very high yield (90% or better) of a single predetermined chlorinated hydrocarbon end product, minimizing the amounts of related chlorinated hydrocarbons produced as by-products. For example in the chlorination of ethylene and/or ethane, to ethylene dichloride, one would expect to also produce at least trace amounts of vinyl chloride, dichloroethylenes, trichloroethylene, trichloroethane, perchloroethane, tetrachloroethane, and pentachloroethane. Thus, in the past, the efficiency of a catalyst was judged by its ability to selectively produce, for example ethylene dichloride, in yields in excess of 90 and preferably in excess of 95%, with corresponding low conversions to other chlorinated hydrocarbons of the ethylene/ethane series, and/or carbon oxides.